The present disclosure relates to apparatus and methods for testing, sampling and/or recovering fluids from a well and/or injecting fluids into a well. Embodiments of the disclosure can be used for fluid testing during recovery and injection of fluids, as well as sampling of the fluids. Some embodiments relate especially but not exclusively to recovery and injection, into either the same, or a different well.
Once a well has been drilled it is “completed” by the installation of casing, valves and conduits to control the flow of the production fluids from the well and convey them to the surface for recovery in the production phase. After completion but before the production phase commences, the well must be tested to determine the quantity and quality of the production fluids flowing from the well. In particular, the well is tested to ensure that no obstructions remain to the flow of fluids from the well, which may have been present during the earlier procedures and provided inaccurate test results. During well test procedures, prior to the production phase, the production fluids are flowed from the reservoir through the casing and the wellhead and christmas tree and into a production flowline that connects the christmas tree to the surface. During initial phases of well testing the production fluids wash out the dense completion fluids used to control wellbore pressure during the completion phases of the well construction, and much of the debris and sand is also washed out of the well at this phase. The early production fluids are often mixed-phase fluids with a mixture of gasses, liquids and solids. They will often have a high gas content, which must be flared off at the surface. The maximum flow rate of the production fluids from the well during well testing is largely determined by the gas content, because flaring is highly exothermic and it is only possible to flare off gasses at a certain rate at the surface. Therefore, current well test procedures are not ideal for some wells because the maximum flow rate of production fluids during well testing might not be sufficient to wash out the completion fluids, sand and other debris from the well. Other limitations in the prior art are also present in current well test procedures.